I do believe there is no 100% cure. But I do think some PNs do get better either with lifestyle changes, and/or some supplements.

One can stop progression if a reason is found, and eliminated, and some healing is possible. The compressive neuropathies can heal. I had hypothyroid compression in my wrists, and they did improve with time once that cause was discovered.

Some Toxin/drug PNs may improve if the offending agent is removed. Some diabetic PNs improve with lifestyle changes.
But often they do not go away completely.

Idiopathic just means no cause yet found. It is not really a true diagnosis either, but a just a descriptive term.

The genetic neuropathies remain progressive however, (until research reveals some way to improve them, say perhaps stem cell treatments or a drug, etc).